Many rockets and missiles include one or more solid rocket motors to generate thrust to achieve and/or maintain flight, and/or to control in-flight direction. A solid rocket motor may include, for example, a motor case and a main nozzle. Typically, the motor case defines a combustion chamber, in which propellant is loaded and combusted to generate high-energy combustion gas. The main nozzle is typically in fluid communication with the combustion chamber and thus receives the high-energy combustion gas. The main nozzle may include a convergent inlet section, a divergent outlet section, and an interposing main nozzle throat. Combustion gas generated in the combustion chamber flows through the main nozzle, generating a thrust.
Solid rocket motors, such as the one briefly described above, are used in both strategic and tactical rockets and missiles. In general, strategic missiles are used for long duration missions, whereas tactical missiles are used for relatively short duration flight missions. Both types of missiles may be equipped with guidance capabilities, whereby valves are employed to divert high-energy combustion gases from the main nozzle to one or more peripheral valve nozzles. The valve nozzles are designed to be used to steer the missile in a desired direction.
Each valve nozzle includes an inlet, outlet and a flow path extending therebetween. Typically, the flow path has a predetermined shape that is designed to provide optimal lateral control. Thus, the predetermined flow path shape is preferably maintained during valve nozzle operation. In this regard, some valve nozzles are formed from material capable of withstanding exposure to temperatures at least up to 5000° F. Although these materials are effective in maintaining the shape of the nozzle flow path, they may conduct heat and transfer the heat to surrounding components. Consequently, surrounding components that may be heat-sensitive, such as valves, may become damaged or may need to undergo more frequent maintenance. Other valve nozzles may be formed from high temperature material having insulating properties; such materials include phenolic. These high temperature materials insulate surrounding components from heat, however, many have ablative properties. Thus, the materials may not provide the desired structural integrity to prevent deformation of the valve nozzle upon exposure to extreme heat.
Therefore, there is a need for a valve nozzle that is capable of maintaining the shape of its preformed flow path; insulating surrounding components from extreme heat exposure; and minimizing erosion of the throat section of the valve nozzle flow path. The present invention addresses one or more of these needs.